Error in SwiftUI

No, it works as is and works in Preview as well:

You may have 2 problems:

• not calling Preview
• gearbox is white on white.

I changed as follows:

struct ContentView: View {
    @State private var selection: String? = nil
    
    var body: some View {
        NavigationView {
            ZStack {
                Image("BACKGROUND")
                    .resizable()
                    .edgesIgnoringSafeArea(.all)
                
                VStack {
                    Spacer()
                    
                    VStack {
                        NavigationLink(
                            destination: GameView(),
                            tag: "jouer",
                            selection: $selection
                        ) {
                            EmptyView()
                        }
                        
                        Button("Jouer") {
                            selection = "jouer"
                        }
                        .padding()
                        .foregroundColor(.black)
                        .background(Color.white)
                        .cornerRadius(10)
                        .padding(10) // Ajoutez une marge supplémentaire si nécessaire
                        
                        Button("Chapitre") {
                            // Code à exécuter lorsqu'on appuie sur le bouton "Chapitre"
                        }
                        .padding()
                        .foregroundColor(.white)
                        .background(Color.blue)
                        .cornerRadius(10)
                    }
                    
                    Spacer().frame(height: 20)
                    
                    HStack {
                        Spacer()
                        
                        Image(systemName: "gearshape")
                            .font(.system(size: 12))
                            .foregroundColor(.blue)
                            .onTapGesture {
                                print("Tapped")
                                // Code à exécuter lorsqu'on appuie sur le bouton d'engrenage
                            }
                        Spacer()
                    }
                }
            }
        }
    }
}

#Preview {  // <<-- ADD THIS
    ContentView()
}

I don't understand what selection does in your code, nor tag.

You can simply replace by

                        NavigationLink(destination: GameView() )
                        {
                                Text("jouer")
                        }

To silence the warning, or use a NavigationStack

Thank you very much for your help! I'm trying to learn on my own without formal training, and I sometimes use the assistance of an AI to learn, hence the potential errors as well. If you have any advice for learning, guides, or videos, I would greatly appreciate it.

Thanks !